DE 10 2013 222 989 A1 discloses a transmission system having a plurality of transmission ratios that can be engaged and disengaged by shift rods that are adjustable by hydraulically actuatable piston/cylinder units. An actuating pressure can be applied by a valve device in the piston/cylinder units. The valve device includes three pilot-controlled shift valves that are coupled to each other by lines and that each have a first or a second shift position for representing the transmission ratios. The actuating pressure is freely adjustable by two pilot-controlled pressure regulating valves and can be forwarded in the direction of the valve device. Piston chambers of the piston/cylinder unit can be brought into operative connection either with the valve device or with a low-pressure region by at least one additional valve unit. In addition, the valve device is connectable to the piston chambers or the low-pressure region by the valve unit.
However, the drawback with the above design is that the additional valve unit includes a plurality of ball shuttle valves, which connect, as a function of the respective pressure that is applied, the piston chambers to either a prefilling valve or to the valve device. Therefore, during unfavorable operating condition trends, such ball shuttle valves may have undefined operating states, which in turn cause unwanted high leakage volume flows. These unwanted high leakage volume flows cause such fluctuations in the profile of a system pressure or, more specifically, the actuating pressure, that both the comfort-oriented and fast transmission ratio changes or, more specifically, the so-called sporty gear shifts, which are to be carried out within shorter operating periods than the comfort-oriented gear shifts, cannot be implemented to the extent requested in the transmission system.